1. Field of the Invention
The present invention relates to an image sensor module, and more particularly to an image sensor module having a reduced manufacturing cost and package volume.
2. Description of the Related Art
Referring to FIG. 1, a conventional image sensor module includes a lens holder 10, a lens barrel 20, and an image sensor 30. The lens holder 10 has an upper face 12, a lower face 14 and an opening 16 penetrating through the lens holder 10 from the upper end face 12 to the lower end face 14. An internal thread 18 is formed on an inner wall of the opening 16 of the lens holder 10.
The lens barrel 20 formed with an external thread 22 is inserted from the upper end face 12 of the lens holder 10, received within the opening 16, and screwed to the internal thread 18 of the lens holder 10. The lens barrel 20 is formed with a transparent region 24 under which an aspheric lens 26 and an infrared filter 28 are arranged in sequence.
The image sensor 30 has a substrate 31, which is a printed circuit board. The substrate 31 has a first surface 32 formed with first connected points 34 and a second surface 33 opposite to the first surface 32 formed with second connected points 35.
The frame layer 36 is arranged at the periphery of the first surface 32 of the substrate 31.
The photosensitive chip 37 is mounted on the first surface 32 on which is electrically connected to the first connected points 34 by wires 38.
The transparent layer 39 is adhered on the frame layer 36 for covering the photosensitive chip 37 and wires 38.
The above-mentioned image sensor module has the following drawbacks.
1. Because the transparent layer 36 is bonded to the lower surface 14 of the lens holder 10 by the adhesive, which may contaminate the surface of the transparent layer 36, poor optical signals may be obtained.
2. When the module is assembled, the transparent layer 36 has to be precisely positioned with the aspheric lens 26 and then bonded to the lens barrel 20. Once the positional precision deviates from the standard level, the overall module cannot be reassembled and has to be treated as waste material.
3. The lens holder 10 has to be additionally provided to combine the lens barrel 20 with the image sensor 30.
4. The substrate 31 is a printed circuit board, which has a higher cost.